package net.minecraft.server.level;

import com.mojang.datafixers.util.Pair;
import com.mojang.logging.LogUtils;
import it.unimi.dsi.fastutil.objects.ObjectArrayList;
import it.unimi.dsi.fastutil.objects.ObjectList;
import it.unimi.dsi.fastutil.objects.ObjectListIterator;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.IntSupplier;
import net.minecraft.Util;
import net.minecraft.core.BlockPos;
import net.minecraft.core.SectionPos;
import net.minecraft.util.thread.ConsecutiveExecutor;
import net.minecraft.world.level.ChunkPos;
import net.minecraft.world.level.LightLayer;
import net.minecraft.world.level.chunk.ChunkAccess;
import net.minecraft.world.level.chunk.DataLayer;
import net.minecraft.world.level.chunk.LevelChunkSection;
import net.minecraft.world.level.chunk.LightChunkGetter;
import net.minecraft.world.level.lighting.LevelLightEngine;
import org.jetbrains.annotations.Nullable;
import org.slf4j.Logger;

public class ThreadedLevelLightEngine extends LevelLightEngine implements AutoCloseable {
	public static final int DEFAULT_BATCH_SIZE = 1000;
	private static final Logger LOGGER = LogUtils.getLogger();
	private final ConsecutiveExecutor consecutiveExecutor;
	private final ObjectList<Pair<ThreadedLevelLightEngine.TaskType, Runnable>> lightTasks = new ObjectArrayList<>();
	private final ChunkMap chunkMap;
	private final ChunkTaskDispatcher taskDispatcher;
	private final int taskPerBatch = 1000;
	private final AtomicBoolean scheduled = new AtomicBoolean();

	public ThreadedLevelLightEngine(
		LightChunkGetter lightChunkGetter, ChunkMap chunkMap, boolean skyLight, ConsecutiveExecutor consecutiveExecutor, ChunkTaskDispatcher taskDispatcher
	) {
		super(lightChunkGetter, true, skyLight);
		this.chunkMap = chunkMap;
		this.taskDispatcher = taskDispatcher;
		this.consecutiveExecutor = consecutiveExecutor;
	}

	public void close() {
	}

	@Override
	public int runLightUpdates() {
		throw (UnsupportedOperationException)Util.pauseInIde(new UnsupportedOperationException("Ran automatically on a different thread!"));
	}

	@Override
	public void checkBlock(BlockPos pos) {
		BlockPos blockPos = pos.immutable();
		this.addTask(
			SectionPos.blockToSectionCoord(pos.getX()),
			SectionPos.blockToSectionCoord(pos.getZ()),
			ThreadedLevelLightEngine.TaskType.PRE_UPDATE,
			Util.name((Runnable)(() -> super.checkBlock(blockPos)), () -> "checkBlock " + blockPos)
		);
	}

	protected void updateChunkStatus(ChunkPos chunkPos) {
		this.addTask(chunkPos.x, chunkPos.z, () -> 0, ThreadedLevelLightEngine.TaskType.PRE_UPDATE, Util.name((Runnable)(() -> {
			super.retainData(chunkPos, false);
			super.setLightEnabled(chunkPos, false);

			for (int i = this.getMinLightSection(); i < this.getMaxLightSection(); i++) {
				super.queueSectionData(LightLayer.BLOCK, SectionPos.of(chunkPos, i), null);
				super.queueSectionData(LightLayer.SKY, SectionPos.of(chunkPos, i), null);
			}

			for (int i = this.levelHeightAccessor.getMinSectionY(); i <= this.levelHeightAccessor.getMaxSectionY(); i++) {
				super.updateSectionStatus(SectionPos.of(chunkPos, i), true);
			}
		}), () -> "updateChunkStatus " + chunkPos + " true"));
	}

	@Override
	public void updateSectionStatus(SectionPos pos, boolean isQueueEmpty) {
		this.addTask(
			pos.x(),
			pos.z(),
			() -> 0,
			ThreadedLevelLightEngine.TaskType.PRE_UPDATE,
			Util.name((Runnable)(() -> super.updateSectionStatus(pos, isQueueEmpty)), () -> "updateSectionStatus " + pos + " " + isQueueEmpty)
		);
	}

	@Override
	public void propagateLightSources(ChunkPos chunkPos) {
		this.addTask(
			chunkPos.x,
			chunkPos.z,
			ThreadedLevelLightEngine.TaskType.PRE_UPDATE,
			Util.name((Runnable)(() -> super.propagateLightSources(chunkPos)), () -> "propagateLight " + chunkPos)
		);
	}

	@Override
	public void setLightEnabled(ChunkPos chunkPos, boolean lightEnabled) {
		this.addTask(
			chunkPos.x,
			chunkPos.z,
			ThreadedLevelLightEngine.TaskType.PRE_UPDATE,
			Util.name((Runnable)(() -> super.setLightEnabled(chunkPos, lightEnabled)), () -> "enableLight " + chunkPos + " " + lightEnabled)
		);
	}

	@Override
	public void queueSectionData(LightLayer lightLayer, SectionPos sectionPos, @Nullable DataLayer dataLayer) {
		this.addTask(
			sectionPos.x(),
			sectionPos.z(),
			() -> 0,
			ThreadedLevelLightEngine.TaskType.PRE_UPDATE,
			Util.name((Runnable)(() -> super.queueSectionData(lightLayer, sectionPos, dataLayer)), () -> "queueData " + sectionPos)
		);
	}

	private void addTask(int chunkX, int chunkZ, ThreadedLevelLightEngine.TaskType type, Runnable task) {
		this.addTask(chunkX, chunkZ, this.chunkMap.getChunkQueueLevel(ChunkPos.asLong(chunkX, chunkZ)), type, task);
	}

	private void addTask(int chunkX, int chunkZ, IntSupplier queueLevelSupplier, ThreadedLevelLightEngine.TaskType type, Runnable task) {
		this.taskDispatcher.submit(() -> {
			this.lightTasks.add(Pair.of(type, task));
			if (this.lightTasks.size() >= 1000) {
				this.runUpdate();
			}
		}, ChunkPos.asLong(chunkX, chunkZ), queueLevelSupplier);
	}

	@Override
	public void retainData(ChunkPos pos, boolean retain) {
		this.addTask(
			pos.x, pos.z, () -> 0, ThreadedLevelLightEngine.TaskType.PRE_UPDATE, Util.name((Runnable)(() -> super.retainData(pos, retain)), () -> "retainData " + pos)
		);
	}

	public CompletableFuture<ChunkAccess> initializeLight(ChunkAccess chunk, boolean lightEnabled) {
		ChunkPos chunkPos = chunk.getPos();
		this.addTask(chunkPos.x, chunkPos.z, ThreadedLevelLightEngine.TaskType.PRE_UPDATE, Util.name((Runnable)(() -> {
			LevelChunkSection[] levelChunkSections = chunk.getSections();

			for (int i = 0; i < chunk.getSectionsCount(); i++) {
				LevelChunkSection levelChunkSection = levelChunkSections[i];
				if (!levelChunkSection.hasOnlyAir()) {
					int j = this.levelHeightAccessor.getSectionYFromSectionIndex(i);
					super.updateSectionStatus(SectionPos.of(chunkPos, j), false);
				}
			}
		}), () -> "initializeLight: " + chunkPos));
		return CompletableFuture.supplyAsync(() -> {
			super.setLightEnabled(chunkPos, lightEnabled);
			super.retainData(chunkPos, false);
			return chunk;
		}, runnable -> this.addTask(chunkPos.x, chunkPos.z, ThreadedLevelLightEngine.TaskType.POST_UPDATE, runnable));
	}

	public CompletableFuture<ChunkAccess> lightChunk(ChunkAccess chunk, boolean isLighted) {
		ChunkPos chunkPos = chunk.getPos();
		chunk.setLightCorrect(false);
		this.addTask(chunkPos.x, chunkPos.z, ThreadedLevelLightEngine.TaskType.PRE_UPDATE, Util.name((Runnable)(() -> {
			if (!isLighted) {
				super.propagateLightSources(chunkPos);
			}
		}), () -> "lightChunk " + chunkPos + " " + isLighted));
		return CompletableFuture.supplyAsync(() -> {
			chunk.setLightCorrect(true);
			return chunk;
		}, runnable -> this.addTask(chunkPos.x, chunkPos.z, ThreadedLevelLightEngine.TaskType.POST_UPDATE, runnable));
	}

	public void tryScheduleUpdate() {
		if ((!this.lightTasks.isEmpty() || super.hasLightWork()) && this.scheduled.compareAndSet(false, true)) {
			this.consecutiveExecutor.schedule(() -> {
				this.runUpdate();
				this.scheduled.set(false);
			});
		}
	}

	private void runUpdate() {
		int i = Math.min(this.lightTasks.size(), 1000);
		ObjectListIterator<Pair<ThreadedLevelLightEngine.TaskType, Runnable>> objectListIterator = this.lightTasks.iterator();

		int j;
		for (j = 0; objectListIterator.hasNext() && j < i; j++) {
			Pair<ThreadedLevelLightEngine.TaskType, Runnable> pair = (Pair<ThreadedLevelLightEngine.TaskType, Runnable>)objectListIterator.next();
			if (pair.getFirst() == ThreadedLevelLightEngine.TaskType.PRE_UPDATE) {
				pair.getSecond().run();
			}
		}

		objectListIterator.back(j);
		super.runLightUpdates();

		for (int var5 = 0; objectListIterator.hasNext() && var5 < i; var5++) {
			Pair<ThreadedLevelLightEngine.TaskType, Runnable> pair = (Pair<ThreadedLevelLightEngine.TaskType, Runnable>)objectListIterator.next();
			if (pair.getFirst() == ThreadedLevelLightEngine.TaskType.POST_UPDATE) {
				pair.getSecond().run();
			}

			objectListIterator.remove();
		}
	}

	public CompletableFuture<?> waitForPendingTasks(int x, int z) {
		return CompletableFuture.runAsync(() -> {}, runnable -> this.addTask(x, z, ThreadedLevelLightEngine.TaskType.POST_UPDATE, runnable));
	}

	static enum TaskType {
		PRE_UPDATE,
		POST_UPDATE;
	}
}